网上的都是自己绘制的或者图片，我的需求是可以随意的自定义底部和顶部的布局。所以自己重写一个，原理就是直接继承 View 来实现一个刮层，让这个刮层和图片以及文字不产生任何依赖，再结合 FrameLayout 将刮层放置最上一层，刮层之下你想放多少图片文字，图片文字要怎么布局摆放都行。由于是FrameLayout ，刮层的上面想加内容都是可以的。如图：
原理：刮刮卡无非就是文本，或者图片，就是我们下边的布局，然后在其上绘制刮奖层，设置DST_OUT，然后把用户触摸绘制上去；这样消失以后就能看到背后的奖了。
布局
<FrameLayout
android:layout_width="350dp"
android:layout_centerInParent="true"
android:layout_height="150dp">
<include
layout="@layout/scratch_view_after"/>
<coordemo.ly.com.myapplication.GuaGuaKaView
android:layout_width="match_parent"
android:id="@+id/gg1"
android:layout_height="match_parent" />
</FrameLayout>
刮一刮控件
public class GuaGuaKaView extends View {
/**
* 绘制线条的画笔
*/
private Paint mOutterPaint = new Paint();
/**
* 遮层画笔
*/
private Paint mMaskPaint = new Paint();
/**
* 最下面画笔
*/
private Paint mBackPint = new Paint();
/**
* mCanvas绘制内容在其上
*/
private Bitmap mBitmap;
/**
* 记录用户绘制的Path
*/
private Path mPath = new Path();
/**
* 内存中创建的Canvas
*/
private Canvas mCanvas;
private boolean isComplete;
private Rect mTextBound = new Rect();
private String mText = "￥500,0000";
private int mLastX;
private int mLastY;
private int measuredWidth;
private int measuredHeight;
public GuaGuaKaView(Context context) {
this(context, null);
}
public GuaGuaKaView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public GuaGuaKaView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init();
}
private void init() {
mPath = new Path();
setUpOutPaint();
setUpBackPaint();
}
/**
* 初始化canvas的绘制用的画笔
*/
private void setUpBackPaint() {
mBackPint.setStyle(Style.FILL);
mBackPint.setTextScaleX(2f);
mBackPint.setColor(Color.DKGRAY);
mBackPint.setTextSize(32);
mBackPint.getTextBounds(mText, 0, mText.length(), mTextBound);
}
@Override
protected void onDraw(Canvas canvas) {
if (!isComplete) {
drawPath();
canvas.drawBitmap(mBitmap, 0, 0, null);
} else {
this.setVisibility(GONE);
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
measuredWidth = getMeasuredWidth();//宽高和父view的相同
measuredHeight = getMeasuredHeight();
// 初始化bitmap
mBitmap = Bitmap.createBitmap(measuredWidth, measuredHeight, Bitmap.Config.ARGB_8888);
mCanvas = new Canvas(mBitmap);
mMaskPaint.setColor(Color.parseColor("#00000000"));//遮层透明
mMaskPaint.setStyle(Style.FILL);
mCanvas.drawRoundRect(new RectF(0, 0, measuredWidth, measuredHeight), 0, 0, mMaskPaint);
mCanvas.drawBitmap(BitmapFactory.decodeResource(getResources(),
R.drawable.award_1), null, new RectF(0, 0, measuredWidth, measuredHeight), null);//遮层
}
/**
* 设置画笔的一些参数
*/
private void setUpOutPaint() {
// 设置画笔
// mOutterPaint.setAlpha(0);
mOutterPaint.setColor(Color.parseColor("#c0c0c0"));
mOutterPaint.setAntiAlias(true);
mOutterPaint.setDither(true);
mOutterPaint.setStyle(Style.STROKE);
mOutterPaint.setStrokeJoin(Paint.Join.ROUND); // 圆角
mOutterPaint.setStrokeCap(Paint.Cap.ROUND); // 圆角
// 设置画笔宽度
mOutterPaint.setStrokeWidth(50);
}
/**
* 绘制线条
*/
private void drawPath() {
mOutterPaint.setStyle(Style.STROKE);
mOutterPaint
.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_OUT));//取俩者的交集
mCanvas.drawPath(mPath, mOutterPaint);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
int action = event.getAction();
int x = (int) event.getX();
int y = (int) event.getY();
switch (action) {
case MotionEvent.ACTION_DOWN:
mLastX = x;
mLastY = y;
mPath.moveTo(mLastX, mLastY);
break;
case MotionEvent.ACTION_MOVE:
int dx = Math.abs(x - mLastX);
int dy = Math.abs(y - mLastY);
if (dx > 3 || dy > 3)
mPath.lineTo(x, y);
mLastX = x;
mLastY = y;
new Thread(mRunnable).start();
break;
case MotionEvent.ACTION_UP:
new Thread(mRunnable).start();
break;
}
invalidate();
return true;
}
/**
* 统计擦除区域任务
*/
private Runnable mRunnable = new Runnable() {
private int[] mPixels;
@Override
public void run() {
int w = getWidth();
int h = getHeight();
float wipeArea = 0;
float totalArea = w * h;
Bitmap bitmap = mBitmap;
mPixels = new int[w * h];
/**
* 拿到所有的像素信息
*/
bitmap.getPixels(mPixels, 0, w, 0, 0, w, h);
/**
* 遍历统计擦除的区域
*/
for (int i = 0; i < w; i++) {
for (int j = 0; j < h; j++) {
int index = i + j * w;
if (mPixels[index] == 0) {
wipeArea++;
}
}
}
/**
* 根据所占百分比，进行一些操作
*/
if (wipeArea > 0 && totalArea > 0) {
int percent = (int) (wipeArea * 100 / totalArea);
// Log.e("TAG", percent + "");
if (percent > 50) {
// Log.e("TAG", "清除区域达到50%，下面自动清除");
isComplete = true;
postInvalidate();
}
}
}
};
/**
* 将布局转换成bitmap
* @param addViewContent
* @return
*/
private Bitmap getViewBitmap(View addViewContent) {
addViewContent.setDrawingCacheEnabled(true);
addViewContent.measure(
View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED),
View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED));
addViewContent.layout(0, 0,
addViewContent.getMeasuredWidth(),
addViewContent.getMeasuredHeight());
addViewContent.buildDrawingCache();
Bitmap cacheBitmap = addViewContent.getDrawingCache();
Bitmap bitmap = Bitmap.createBitmap(cacheBitmap);
return bitmap;
}
}
GitHub地址：